These devices can be very reliable when setup correctly.
Start here:
Then over here:
You can also try replacing the battery, not all batteries are created equal, regardless of how new they are.
Sometimes there is nothing you can do about it, some members have found they have a neighbor with high powered wifi blasting on the same frequency as their ST zigbee and diplomacy failed to resolve the issue.
Finally, you don’t have to remove a zigbee device to re-pair back to the hub. Just put the hub into discovery and push the button on the sensor a few times and it should pop back in.